Add parameterized object read/write benchmarks

[konradgithuup]

Replace object read/write benchmarks with a parameterized benchmark under the path /object/object/rw.

The benchmarks consist of read/write benchmarks for

• single and batch operations
• sequential, random and zipfian access patterns
• variable block sizes
• variable read/write ratios

The parameters are incorporated into the benchmarks name
/object/object/rw/{PATTERN}{-batch}? <{RATIO}w> {BLOCK_SIZE}
/object/object/rw/zipf-batch <0.50w> 1MiB
Depending on the block size it is either displayed in KiB or MiB in order to take up less space.

For the variable read-write ratio to work we have to write into the file first.
To benchmark write operations on an empty file instead, a separate write benchmark is also included.